In previous chapters, we looked at building web applications and REST APIs with Spring Boot. We discussed advanced Spring Boot features, such as externalized configuration, monitoring, embedded servers, and deploying to the cloud.

In this chapter, let's turn our attention to data. In the last few years, there has been a rapid evolution in our understanding of where we store our data and how we store data in databases.

There are a number of new database options today.

With a variety of data stores in play, how we interact with these data stores is becoming even more important. While Java Persistence APIs (JPAs) made it easy to communicate with relational databases, Spring Data aims to bring in a common approach to talk to a wider variety of data stores—relational or otherwise.

The following are some of the questions we will answer during this chapter:

• What is Spring Data?
• What are the aims of Spring Data?
• How do you talk to a relational database using Spring Data and Spring Data JPAs?
• How do you talk to a non-relational database such as MongoDB using Spring Data?